Computational Chemistry and Molecular Modelling
A. Clark Group
Molecular photochemistry
We have several projects related to molecular photochemistry and continue active research in this area with an aim of understanding and rationalizing unique experimentally observed phenomena.
Example 1: Optical properties of chromophore aggregates
The diimide perylene motif exhibits a dramatic intensity reversal between the 0-0 and 0-1 vibronic bands upon pi-pi stacking; this distinct spectral property has previously been used to measure folding dynamics in covalently bound oligomers and synthetic biological hybrid foldamers. It is also used as a tool to assess organization of the pi-stacking, indicating the presence of H- or J-aggregation.
We have therefore examined the optical properties of gas-phase perylene tetracarboxylic diimide (PTCDI) and its chromophoric dimer as a function of conformation in order to relate the excited state distributions predicted by exciton theory with that of TDDFT. Using ground and excited state geometries, the FC factors for the lowest energy molecular nature electronic transition have been calculated and the origin of the intensity reversal of 0-0 and 0-1 vibronic bands has been proposed.
Example 2: Electronic-vibrational coupling in charge transfer processes
Theoretical studies of the betalains (betanidin, betanin and geomphrenin) have been performed at the B3LYP/6-31G(d) level. As dyesensitizers in DSSCs, only little is known about their molecular properties relevant to the electron injection process. Here, ground state geometries, electronic transition energies, oxidation potentials, and proton affinities are reported. The HOMO->LUMO transition describes all lowest singlet excited states. The ground and excited state oxidation potentials are calculated to be 1.0 V and 1.3 V (vs. NHE), respectively. Deprotonation order is determined by calculating proton affinities at different sites. The vibrational–electronic coupling and its role in the electron transfer process are analyzed.
Recent News!
4/08: Aurora recieves Young Faculty Performance Award from College of Sciences.
4/08: Undergraduate research Brandon Kvamme presents his work at the WSU COS undergrad poster session. Good Job Brandon!
4/08: Murdock Partners in Science Grant proposal is funded to allow local High School Teacher MaryAnn Thornton to work in the lab for the next two summers.
1/15/08: Grad. Natalia Zhackarova joins the group. Welcome Natalia!
1/15/08: Undergrad. Stephanie Westcott joins the group for Chem 499. Welcome Stephanie!
8/15/07: Post-doc Matthew Wander starts fresh from his Ph.D. at SUNY Stonybrook. Welcome Matthew!
8/15/07:Post-doc Changyong Qin obtains a faculty position at Vassar College. You will be missed CY!
8/07: Aurora presents invited talk at Boston ACS Meeting "The role of surface charge density in Ln(III) and An(IV)-(VI) hydration"
7-8/07: Dr. Adriana Dinescu (INL) works for the summer on hydration properties of Ce(III).